As it grows in popularity, vitamin D's role is debated

VITAMIN D SOURCES

Sunlight: The National Institutes of Health recommends 10 to 15 minutes of sun exposure on arms, legs and hands two to three times per week without using sunscreen. People with dark skin may need additional exposure.

Supplements: While researchers continue to debate the proper daily dosage for vitamin D supplements, they agree that people should take vitamin D-3 (cholecalciferol form) instead of D-2. Vitamin D-3 is more potent, and the body absorbs it more easily.

Oily fish such as salmon, tuna, mackerel and sardines: A 3-to-
3.5-ounce serving provides about 90 percent of the daily value for vitamin D.

A flurry of recent reports trumpeting the health benefits of vitamin D have vaulted the supplement to a starring role on the merchandise shelves at Burns Drugs in La Jolla.

Pharmacist Wayne Woods, who owns the store, said he's seeing a growing number of customers asking for bottles of high-dosage vitamin D.

“We barely carried it before, but physicians are recommending it as a normal supplement on a daily basis in addition to taking your multivitamin,” Woods said.

Vitamin D's role in bone health has long been known – think rickets in malnourished children and osteoporosis in older people. But research tying vitamin D deficiency to cancers, heart disease, diabetes and other illnesses has transformed the nutrient into a potential miracle cure. A global network of influential scientists said daily intake should be up to 10 times higher than the U.S. government's current recommendations.

Yesterday, more than 100 physicians, nutritionists, acupuncturists, massage therapists and others gathered at the University of California San Diego for a daylong conference extolling vitamin D.

But not everyone is as enthusiastic, especially after a succession of reports dimmed the spotlight on vitamin supplements. Last month, two major clinical trials debunked vitamin B as a treatment for Alzheimer's disease and vitamins E and C as protectors against cancer.

The scientific uncertainty has generated debate over the virtues and dangers of vitamin D. One big reason for the researchers' disagreements: The most promising studies suggest a relationship between low vitamin D intake and many diseases, but they have failed to show a direct cause and effect.

Skeptics of dramatically boosting vitamin D supplements point to the lack of large-scale, random and “double blind” clinical studies comparing the nutrient to placebos. Dermatologists also have bristled at suggestions that people spend more time in the sun to increase the natural production of vitamin D.

Those concerns didn't deter several longtime advocates of vitamin D supplements at yesterday's meeting, including Dr. Robert Heaney, a professor at Creighton University in Omaha, Neb.

Heaney said studies conducted in North America and Europe found low vitamin D levels in as many as 95 percent of participants. “I think we can take it as a given that the vast majority of patients in the U.S. are vitamin D deficient,” he said.

People get most of their vitamin D from exposure to sunlight, according to the National Institutes of Health. Spending 10 to 15 minutes outdoors two to three times each week is typically enough.